Problems with Measure lines, keys, clefs, and time signatures

Hi there,
I have had the Musescore 3.0 for a while and I am having a very interesting situation regarding this new update. When downloading this new app, I decided that I wanted to transfer some of my unfinished work onto the new Musescore, so I can finish the music there. It was fairly easy to download the app and transfer the music but, the results of when I opened the sheet music, I was utterly disappointed. In almost every measure, there were repeated clefs, that were irrelevant because I did not need a clef change, and some of the clefs I couldn't even delete. This also happened with the key and time signatures, but I was abled to delete those. There were also multiple measure lines extending into a different staff, making the measure line seem very thick and black. I want to download more of my unfinished work onto the new Musescore, because I love this app/website so much, but after the experience I had with download at least 7 of my old scores, I am waiting and finishing my work on the previous Musescore. I really hope you can fix this! Thank you so much for all your hard work and effort!!